Many optical systems require a wide field of view, to search a large area quickly, and a narrow field of view, to provide detailed information on an item of interest. Previous methods of achieving this dual field-of-view (FOV) capability have involved complex and space-intensive multi-element optical assemblies that are complex to design and manufacture. Low-cost, space-limited applications previously had not been able to incorporate dual-field-of-view capability.
Dual FOV systems provide both a wide field of view and a narrow, or magnified, field of view of the same perspective. Typical examples of non-simultaneous dual FOV systems are the optical zoom lens assemblies found in consumer video camera systems. Such systems work by moving lens components with respect to one another to transition between minimum and maximum FOV extents, termed “wide” and “zoom,” respectively. Such implementations involving moving lens components are bulky, expensive, and can be prone to damage, as from shock-induced misalignment of optical components, or failure of servomotors used to reposition the optical elements with respect to each other. Such switched-FOV systems are also unable to provide both fields of view simultaneously since they require the movement of lenses to switch between fields of view. Other dual FOV optical assemblies eliminate the requirement for moving lenses, but still involve substantial gaps between the optical components, and are thus similarly bulky, expensive, and fragile.
Systems employing what is known as “digital zoom,” which relies on image processing techniques to digital create a narrow field of view from an image acquired from a wide field of view, can exhibit image degradation in the digitally enhanced narrow-field-of-view images, such as pixilation, enhancement algorithm artifacting, and noise. Digital zoom systems are thus frequently inadequate for many applications.